As some of you, and I hope all of you, have noticed by now when you create / expand / extent / delete a datastore a rescan of your HBAs will automatically be initiated. This however can lead to a “rescan storm” when you are building a new environment.
You can imagine that it’s pointless to rescan your HBA 25 times in a row when you are adding more than 1 new datastore. I can even imagine you would like to be in control; when, which server and at what time. This behavior was introduced with vCenter 2.5 U2 I believe but as I just found out can be disabled. Now keep in mind that disabling is not a best practice. This should be avoided as a default setting but will come in handy when you are building a new site.
- Open up the vSphere Client
- Go to Administration -> vCenter Server
- Go to Settings -> Advanced Settings
- If the key “config.vpxd.filter.hostRescanFilter” is not available add it and set it to false
Make sure to set it to “true” as soon as you are done because you would like to make sure the environment is consistent in the future when you or your customer is adding/removing/expanding a datastore.
Nice!! THX! I’ll be on 4.0 by the end of the month, But do you know of a way to do this in 3.5? I tryed the steps outlined for 4.0 but that did not work
Yet another very useful vSphere/Storage tip…I like this “rescan storm” term very much..I’m aware of some other terms like “alarms storm” in vCenter and “boot storm” in VDI, but this is the first time to know about this one 🙂
Duncan, are you about to create a new “vCenter Advanced Options” page ? I’d love it 🙂
You can also avoid this by presenting the LUNs to one host before creating the VMFS storage, and only then presenting to the rest. Then rescan the other hosts one by one.
However this is not always possible if you don’t have access to the SAN, so a good tip!
This article describes how to turn the automatic rescanning of your HBA’s back on:
http://kennethvanditmarsch.wordpress.com/2009/10/09/automatic-rescan-of-your-hbas-how-to-enable-this-again/
Duncan,
What is the default time of the storage resource usage, and is it configurable to something faster or slower?